**注意 - 1**：`listeners`参数不可以为默认值`listeners=PLAINTEXT://:9092` , 否则JavaApi可能连接不上。
```properties
listeners=PLAINTEXT://192.168.8.110:9092
```
**注意 - 2**：开放端口
```shell
firewall-cmd --add-port=9092/tcp --permanent
firewall-cmd --reload
firewall-cmd --list-port
```
---
```java
public class ConsumerBuilder {
public static void main(String[] args) {
Consumer consumer = new ConsumerBuilder().build();
consumer.subscribe(Arrays.asList("gosuncn"));//订阅的主题列表
while (true) {
ConsumerRecords<String, String> records = consumer.poll(100);
for (ConsumerRecord<String, String> record : records)
System.out.printf("偏移量 = %d, 键 = %s, 值 = %s%n", record.offset(), record.key(), record.value());
}
}
private Properties props = new Properties();
{
props.put(ConsumerConfig.GROUP_ID_CONFIG, "test");
props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true");
props.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "1000");
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
}
public ConsumerBuilder() {
this("192.168.8.110:9092");
}
public ConsumerBuilder(String bootstrapServers) {
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
}
public Consumer build() {
return new KafkaConsumer<>(props);
}
}
```
```xml
<dependencies>
<dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka-clients</artifactId>
<version>0.10.2.2</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.7.0</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
```
> 特别注意：`ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG`一定一定要和`listeners`相关参数保持一致。
